This invention relates to tuner circuits and more particularly to such circuits where the channel acquire time is such that the tuner can sequentially present different channels to a viewer in a manner that the different channels are perceived as being simultaneously presented.
There are many situations where it is desired to display more than one video image (channel) at the same time. One such situation is the now popular picture-in-picture where a viewer may create on his/her display (such as a TV screen, PC or other device) a main picture and a window within the main picture to as to allow the viewer to simultaneously view a second picture.
When such picture-in-picture images are being viewed, the desired channels must be decoded from a multiplexed incoming signal such as an RF signal. The selection process for each channel requires the use of a tuner, a demodulator and a decoder all working in conjunction with a video processor. In the typical situation, each picture will have its own tuner, demodulator and decoder components. Thus, there is a cost added to any system where multiple pictures are required.
In addition to the cost, there is a size penalty that one must pay for multiple tuner systems. This size becomes important as the housing in which the television or other display device (such as a PC, cable modem, personal communication, or the like) becomes smaller.
One major problem that would be encountered if a single tuner system were to be shared between two or more pictures (each tuned to a different channel) is that the channel acquiring time of the tuner is so long that significant picture information is lost. Thus, either the main picture or the window picture (or both) are reduced in quality below an acceptable level.
These and other objects, features and technical advantages are achieved by a system and method which uses a tuner capable of acquiring a selected channel quickly enough so as not to lose enough signal to seriously degrade the video signal. It is recognized that one or two sync cycles could be skipped and the video signal, because of its high redundancy content (which is needed to refresh the screen), would not be seriously degraded. This situation is not true of audio information where degrading should occur if even a single sync cycle is missed. Taking advantage of the redundant video information then, in one preferred embodiment, a first tuner is used to decode a first, or main, signal (this would be the channel on which the user would be listening to audio if audio is desired) and a second tuner is used to provide two or more channels for presentation of the xe2x80x9cwindowxe2x80x9d images in association with the main channel. The tuner is designed to acquire selected channels within several sync cycles so that as the channels change, the image does not appear to be degraded.
This system is useful, for example, in a TV system in which a user watches (and listens) to one channel (the main channel) and several other channels are presented (without audio) concurrently on the screen. The system could also be used with a single tuner controlling several channels if the listener does not require audio, for example, in a PC application, or for a security monitoring. In such a system, audio, if desired, could be provided by a separate tuner. Audio could also be provided by the active video tuner if audio compression, or other techniques, is used to bridge the gaps that occur when the tuner is processing signals on the other channels. Note also that instead of images, the same tuner could be used to decode other types of information content from different channels and to present the different information contents to the user such that the user perceives the information as coming at the same time.
It is a technical advantage of my invention that a single tuner system and method is constructed to allow that tuner to sequentially decode several RF channels and to present the resulting images to a display such that the user sees the images simultaneously.
It is another technical advantage of the invention that a system is designed to allow for the sequential decoding of information signals from different channels and for the presentation of the decoded information to a user such that the information from the different channels is perceived as coming to the user simultaneously.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.